Photographic elements composed of orientable vinyl fluoride polymers



July 3 1947. P. R. Aus'rlN 2,423,749

PHOTOGRPHIC ELEMENTS COIPOSD OF ORIENTABLE VINYL FLUORIDE POLYIIERS Filld latch 16, 1944 GELATIN SILVER HALIDE LAYER GELATIN SUBLAYER POLYVINYL ACETATE VINYL FLUORIDE POLYMER ...Nrulb INVENTOR. PAUL RQLLAND AUSTIN A T TORNE Y acteristics which adverselyafect the the gelatin coated films Wa ,film element Vby changes in "'essing solutions and 'y vinyl fluoride polymer.

are transparent flexible films comprising a radiation-sensitive water-permeable layer and a sup- Patented July 8, 1947 PH'roGnAPmo ELEMENTS ooMPosnD F (/)RIENTABLE FLUQRIDE POLYMERS .raul Renaud Austin, Wilmington,

. to E. I. du-Pontde Nemours & Company,

Del., assignor v d wii- Y, mington, Dei., a. corporation of Delaware nppueanonfMarehis,'1944, serialno seesoov This invention relates to tum of Va radiation-sensitive material. Morepar- -ticularly, it relates to photographic film elements o which comprise'a supportcomposedof an rv'oritable vinyl-fluoride 'polymer bearing atleast Y new photographic elev ments which comprise a support composed'of an o Y orientable rvinyl-fluoride polymer bearing a' strafionim. (cies- 9) f.

in'lamrnability.V The radiation-sensitive waterpermeable layers furthermore aregnot adversely aifected'by the chemical nature of the support.

The polymers, moreover, when heated at normal Vpressure have a softening point' above l`50fC.

The supports can be made by depositing a Vvinyl fluoride polymer from a solvent solution one water-permeable colloid layer which contains a light-sensitive silver halide.

Numerous materials havebeen proposed for useV 'as thesupports or base for photographic films. f The materials'which have been most' widelyused 'on a commercial'scale, however, Aare the fcellulose esters. Of these, cellulose nitrate has been Vgenerally used `for cinematographic films, but has The untreated material is inflammable and often has Van Yexo plosive rate of burning." Thevarieties 'which'are several distinct' disadvantages.

plasticized with agents to lreduce the burning rate are apt' to disc'olorh onv aging. The films,V moreover', are sensitive to water and lack dime'n-L atively noninflammable and form clear transparent films,Y they have high waterabsorption charstability of films made therefrom. In addition.

becomebrittle'a't low humidities. Various synthetic resins have Ybeen proposedv as film base buthave not been used in commercial production.

dimensional sional stability. CelluloseL esters of lower fatty Y acids areialso widely used and while theyA are rel- An object of this invention is to provide a new i' and commercially practical photographic iiim element. A further object is to provide a clear transparent photographic film which remains permanently clear. Another Objectis to lprovide which is substantially unaffectedV humidity and photographic prochasv dimensional stability. A still further object is to provide a photographic nlm element which has good stiffness (viz is not limp) but retains excellent flexibility in thin films (e. g., 0.002 to 0.0 leinch'thick) Still another object is to provide such an element which is of a low degree of fiammability.

The photographic elements of this inventionv comprisea layer of radiation-sensitive material,

imposed' ona support composed of an orientable The preferred elements port composed of such polymers having a. thickness of 0.002 to 0.01 inch. "I'he lms are further characterized by possessing good stiffness with` ilexibility and high dimensional stability, and are clear and transparent and are of a low degree of v'onto a hot smooth surface such' as a casting wheel, band, etc., of the type used in casting cellulose derivative lms. The solvent is then removed by allowing itto evaporate and withdrawing it from the casting zone.

To obtain orientable vinyl nuonde polymers as distinguished from the less desirable unorientable polymers which do not "have the required Ystrength andtoughness for good film base a. mixture of vinyl fluoride and-from 0.005 to 5% by weight (basedon the vinyl fluoride) of an organic yperoxy compound is subjected, in a reaction vessel, to a pressure of at least 1 50 atmospheres at a temperature of 30 to 25.0%y C. for a pe= riod of several hours. Detailed methods of preparing the orientable vinyl fluoride polymers areV described in Coffman 8L Ford copending application, Serial Number 510,966, filed November 19,

. Procedure A A stainless steelreaction vessel capable of with=V standing a pressure in excessof `1000 atxriosv pheres and provided with heating and cooling de-` vices is sweptwith oxygen-free nitrogen and charged with 200 parts of deoxygenated watery and-0.2 part ofbenzoyl peroxide which occupy labout V1A ofthe total volume of the vessel. It is then closed, the nitrogen is removed by evacuation, and 100 partsof vinyl fluoride monomer con- Y Y taining 20 PLVP. Mgof oxygen and a trace of aceti and heating and agitation are-begun. When the Vylene (less than 50 parts per million) is admitted. The vessel is fitted with temperature and pressure recording and controlling instruments,

and is connected to a storage vessel containing monomeric vinyl fluoride of the same purity. The reaction vessel is placed in reciprocating agitator temperature within the reactor reaches 78 C. additional vinyl fluorideis admitted from the storage vessel to raise the pressure in the system to V250'atm. Reaction sets in and the temperature is maintained at 80, and the pressure is maintained at250 atmospheres by addition of vinyl fluoridemonomer from the storage vessel. `After 15 hours the reactionis complete, 80% of the polymerization having .occurred during `the ilrst two hours.

1943. A representative practical procedure fol- ,f flows: f

. 1 The reactor is cooled, pressure is released, and the product is discharged. It is a friable WhiteV cake consisting of 62 parts of vinyl fluoride polymer after washing and drying. The vinyl fluoride polymer is completely soluble in hot dimethyl formamide to the extent Yof -20%, and these solutions when poured on a smooth surface and warmed to drive oil the solvent give tough lms, which-when quenched by bringing to a temperature above the softening temperature and quickly cooling are clear, transparent, colorless, and remarkably free from optical graininess.

The polymers are shown to be orientable by 1 means of a simple test. A lament or narrow strip,

of pressed iilm is subjected to longitudinal-stress. It elongates up to severalhundred per cent, namely, at least 100% and up to 400% ormore in contrast to norientable vinyl fluoride polymer .which elongates only a few per cent until the ultimate tensileu strength' is exceeded and Athe sample breaks. The orientable polymers before orientation show X-ray diffraction'patterns char.-

lal'steristic of .a crystalline powder while after orientation by cold drawing. the polymer showsan characteristic of an X-ray diffraction` pattern oriented liber.

The preparation of photographic elements from the orientable vinyl `fluoride polymers is further illustrated in the following,;examples.

. Y ExamplewY A vinyl fluoride polymer iilm-0.005` inchthick uoride'polymerscan be cast from solvents otherV Additional solvents intone,'mesityl oxide, aniline, phenol, methyl ben- Y prepared by casting a dimethylformamide solution containing 15% by weight of the orientable vinyl fluoride polymer described in Procedure A is subbed with avsolution of lpart` of gelatin dissolved 'in 5 partsof 90% formic acid and 94 parts of dimethyl'formamide and is dried at 100 C.

`It is then coated with a vlight-sensitive gelatinsilver halide emulsion. VThe-,resulting lmdries rapidly to give a smooth, even, light-sensitive ele- A ment which after exposure is processed by standard methods to a. picture of excellent quality. The

film` before or after processing can be folded and struck sharplyor bent repeatedly without breaking and the final picture shows no change in dimensions from-'the original unexposed ele ment. d

` Example 2 A vinyl fluoride polymer lilm Las shown in the A ligure .of the accompanying drawing which constitutes a part of `this specication, of 0.005 inch thicknessprepared by calendering the polymer of ProcedureA is coated with a thin layer of polyvinyl acetate 2 by` dippingin a 2% solution `of.`

polyvlnylacetate in 50-50 acetone dimethyl formamine and then .drying at 150 C. for ve minutes. The resulting iilm is subbed with a gelatin-ace- Y tone subbing solution to form a gelatin sublayer .3 which is then coated with a gelatin-silver halide emulsion to form a layer 4. The resulting film has, in addition to the `properties possessed by the iilmof Example 1, an extremely highI degree of adhesion between the base and gelatin coating.

Example 3` A nlm prepared from the vinyl fluoride polymer prepared by Procedure A above is dipped in a solution of the following composition:

- Parts Vinyl nuoride polymer (Procedure A) 1 Dimethyl formamide 49 Nitrocellulose 2 Acetone 48 4' 'I'he film after dipping is dried at 100 C. for 1/2 hour and subbed with the following solution:

Y Parts Gelatin 5 Sa1icylieacid 2 `Water 20 VEthanol 270 Acetone 100 After drying for l@ hour at 60 C. the illm isv coated with` a gelatin-silver halide emulsion and dried to yield a light-sensitive element of excellent toughness-durability, and water resistance. f i

',The parts referred to in the above procedures and examples are parts by Weight.` Y

The invention as stated above is not limited .to the specific vmaterials andV embodiments 'set forth above." Other vinyl fluoride polymers which are capable of .orientation `by coldV drawing (as .evidenced by, the fact that after cold drawing they show anX-ray dilractiondiagxam characteristic-of an oriented material) and having a softening point atV atmospheric pressure above 150? C. can be used in likemannerras the support for water-permeable colloid layers whichare responsive to `photographic processing.. 'I'he vinyl than those given above. clude tetramethylene .cyclic sulfone, nitroparaffins, e. g., nitrobutane, cyclohexanone, dibutyl kezoate, phenyl acetate and diethyl phosphate.

Y This invention also contemplates fthe use of interpolymers of vinyl iuoride with minor portions (20% or less by weightiof -other polymerizable olei'lnic compounds including vinyl and'vinyll idene compounds, halogenated ethylene andthe like. with 1-20%,by weight of such interpolymerizable materials as vinyl acetate, methyl methacrylate.-

tetraiiuoroethylene, diand tri-fl'uorocthylenea` ethylene, etc., can be used in preparing the light-- sensitive elementsA of this invention.V Such products being composed chiefly of vinyl'fluoride have properties similarto polymers preparedV `from pure vinyl fluoride with minor variations in solubility, `stiii'ness, toughness, softening point, llammability, and so forth. i

Theiilm supports used in fabricating the novel photographic elements of this invention are notlimited -to vinyl fluoride polymers alone. In general, it is unnecessary .to add a plasticizer to the vinyl fluoride polymer film support, as the unmodified polymer contains all of the properties desirable in a iilm `base or support. Modifying agents such as plasticizing or softening agentsV may be natural or synthetic.. Suitable additional colloids include the polyvinyl alcohols includ- Y ing the partially hydrolyzed polyvinyl acetates,`

and mixed polyvinyl-chlorlde-acetates and hydrolyzed interpolymers of vinyl .acetate with un- Thus the interpolymers of vinyl fluorideV saturated compounds for example, maleic anhydried, acrylic acid'esters. etc. of the last mentioned types are 2,276,322 and 2,276,323. y c

' Still other colloids include hydrophilic partially disclosedfin U'. S. P.

y substituted polyvinyl esters and'acetals and mixtures' such `as those in U. S. P. 2,245,218 and the low substituted cellulose'esters of rvsaturated aliphatic monocarboxylic acids of 2 to 4 carbon atoms and low substituted cellulose ethers, e. g.,-

methylcellulose, ethylcellulose, benzylcellulose, etc. Among the natural colloids may be mentioned, casein, albumin, gelatin, gum arabic, agar- `agar, polyglycuronic acid, etc.

Various radiation-sensitive materials may be present' in the light-sensitive layers.A In addition to light-sensitive silver salts such as silver chloride, silver bromide, silver-chloride-bromide,

Isilver-chloride-iodide and similar mixtures there may be utilized bi'chromated hydrophilic colloids, e. g., albumin, gelatin, gum arabic.-4 polyvinyl a1- cohols, or glue. Other light-sensitive materials Suitable colloids include light-sensitive iron salts `and diazonium chemicalsA may also be ports hereof.

The water-permeablecolloid.:layers may conquinoneimine or azomethinefdyes on color coupling development, ofvsilversalt images or of forming azo dyes on coupling, e. g., by an' azo re- 'I'he polyvinyl fluorides may be used to impart their desirable properties to other polymers by means of surface coatings 'thereby forming a laminated lm element. Thus, the fire hazard of cellulose nitrate films may be substantially lowered by surface coating with a vinyl fluoride polymer. A similar surface coating of cellulose acetate lm leads to a great improvement in ilexibility and water resistance.

The vinyl-fluoride polymer supports may be of different thicknesses depending on the use to which thenished article is to be put. In general, due to the increased toughness of suchl polymers much thinner films are feasible than in the case of the cellulose esters. This is a definite advantage in the case of cine film and film for aerial photography because a lgreater length of films can be placed in each reel, or spool.

In the caseof lm for medical or industrial X-ray usage, the support or a stratum on the support can be dyed'or tinted blue, green, etc.,

' to vfacilitate the inspection of the radiographs and/or to Aminimize eye strain.

Thephotographic lms of this invention possess many outstanding advantages. They are characterlzedby unexpectedly high flexibility and strength, practically completev water resistance, and ,absence of firev hazard, a combination of properties not possessed by the nitrocellulose or cellulose 'fatty acid ester films. 'I'he great strength andflexibility of the present film manidride of fulgenic acid and layers of fluorescent imposed-on the novel supi tain immobileornon-diilusing dye in termediatesA or color formers which are capable of forming versalprocedura `*Azplurality of the above layr ers can be imposed on a singlesupport. For instance, a multilayer; element for v11i-colorV photography may contain a yellow filter layer and a `plurality of differentially sensitized silver halide colloid emulsion layers containing color-former nuclei or` compounds which are `so larranged fests' itself in the case of perforated cinematographic films in a large increase in the life of such films which are continually exposed to the wear of projection. K

The flexibility and toughness of the film support of the present, invention is strikingly demonstrated when vmeasurements are made at low relative h'umidities.v Thus, cellulose acetate film,

after exposure to an atmosphere of 50% relative humidity at' room temperature withstands about l5 bends in the Pfund flexometer and when ,bonedry, less than 10 bends. On th other hand, `vinyl fluoride polymer illms are not affected by 200 fiexes (under` either condition) and in fact,

' when tested on the VSchopper exometer the films and sensitized that they record aportion-of the light in the visible spectrum. Such `elements may contain an antihalation layer such as a. gelatin layer containing actinio-light-absorbing dyes or` pigments or colloidal silver. Water permeable colloid layers, e. g., gelatin containing removable filter dyes may also be present.

Thin coatings of otherpolymeric vmaterials may be applied as surface coatings to improve the anchorage between the' water-permeable photographic responsive layers and the vinyl iiuoride polymer support. Materials suitable for such uses are nitrocellulose, cellulose esters, lwater-sensitive polyvinyl compoundse. g., polyvinyl acetate hydrolyzed-or partially hydrolyzed polyvinyl acetate, and interpolymers of vinyl acetate with other vinyl or vinylidene compounds or terminally unsaturated olens. A particularly desirable application of this type of coating is shown ,in Example 2.where a thin coating of polyvinyl acetate o! less than 0.001 in. thickness iscoated on the vinyl fluoride polymer. Such films may then be subbed by the samelmeans employed with nlms consisting solely of the overcoating p01?- mer. This gives excellent anchorage between the base and the colloid layer, e. g.. the lightsensitive silver hallde layer.

Ystored at 50% relative humidity withstand over 9000 folds before breaking.

- The high degree of flexibility and toughness is "particularly evident in the case of a film coated with photographic emulsion. Thus the standard commercial, photographic lms composed of cellulose esters having a gelatin silver halide coating break in two when bent sharply, between the thumb and index finger with the gelatin coatring outside. The photographic nlms of this invention do not break although the emulsion. coating when'brittle may develop a crack.

' The low water resistance of cellulose ester nlms manifests itself mainly in two ways in the preparation of light-sensitive elements. First, during the drying operation after coating, the cellulose ester film absorbs a relatively large amount of water from the emulsion, causing non-uniformities, streaks and splotches in the emulsion coat. Second, the sensitivity of cellulose esters to water leads to deformation ofthe film itself incoating. The films of the present invention are completely free from these defects. The dry iilms of this invention absorb less than 0.3% of water when placed in contact with water at 20 C. for one hour. Even when soaked for 24 hours in water,

the ims of this invention absorb less than 0.5% water and show practically no change in dimensions. In contrast to this. films of cellulose acetate and nitrocellulose absorb about 3 to 5% of water under these conditions. Deformation during coating does hot take place. The coated photographic film elements evidence no distortion or deformation and are particularly useful in the graphic arts, aerial photography and map-making where distortion of images due to linear or i changes in the lm base during processing t be at an absolute minimum. As an additional advantage, the strength and stiffness of vinyl fluoride polymer lm elements after soaking for 24 hours is not appreciably less than that of the dry film.

The nlm supports of the present invention do evidence any hydrolysis or decomposition on prolonged treatmentwith water anlphotographic processing solutions or i extended exposure to` This fact is of extreme imhumid conditions. portance in lms used in color photography where it is recognized that slow hydrolysis and decomposition of the common cellulose esters lead to` a degradation of the dye intermediates or dyes employed in forming the colors.y The film elements of this invention being resistant to hydrolyzing influences met with in the processing and storage of photographic lm are entirely satisfactory for archival and documentary records irl-color.

The films of this inventiornas has `been pointedy l out above, burn with diiiculty and even when herein possess a combination of properties ideally suited forall of the known photographie applications where a flexible material is employed. No limitation appears to exist upon their. use in the photographic and photomechanical industries; that is, they can be used with the advantages outlined above as cut or rolled lm, in amateur or 'professional cinematography,` the recording 0f ingle. transparent flexible support composed es" sentially of orientable polyvinyl uoride which hasa softening point-above C., having superposed thereon in order a thin layer of polyvinyl acetate, a silblayer of gelatin and a. gelatino-silver halide emulsion layer the said thin layer of polyvinyl acetatel being interunited with the said support andthe said sublayer whereby there is a high degree of adhesion vbetween the support and gelatin coating.

PAUL `ROLLAND AUSTIN.

REFERENCES CITED The following references are of record in the iile of this patent: l

UNITED 'STATES Y PATENTS Number Name Date 1,627,935 Stincheld May 10, 1927 2,099,976 Hagedorn Nov. 23, 1937 2,237,017 Thinius Apr. 1, 1941 1,425,130 Plauson Aug. 8, 1922 2,224,663 Berg et al. Dec. 10,; 1940 2,298,039. DAlelio Oct. 6, 1942 1,721,034 Ostromislensky July 16, 1929 2,074,647 Hagedorn et al Mar. 23, 1937 2,362,960- Tl'iomas Nov, 14, 1944 OTHER REFERENCES Journal of the American Chemical Society, vol. 56 (1934) pp. 12370-1874. 

